1. Field of the Invention
The present invention relates to the separation of vital wheat gluten and starch and, more particularly, to a wet process for fractionating vital wheat gluten, starch, bran and germ from the whole wheat kernel with minimum damage to the functional, chemical and biological characteristics of the wheat kernel components.
2. Description of the Prior Art
The commercial production of vital wheat gluten and the separation of starch therefrom has been accomplished in the past using wheat flour or second clears (a small fraction of the flour stream) as the starting material by the "dough ball" process and modifications thereof, which processes essentially separate the wheat starch from the gluten protein. In one process, the gluten is maintained as a single coherent mass and the starch is washed out of a flour and water dough. Another process disperses the dough in water and recovers the gluten particles on a screen. Variations of the basic dough ball process utilizing wheat flour account for all of the vital gluten produced commercially today.
No known gluten production process employs the whole wheat kernel as the starting material. This is probably because production of vital wheat gluten is a comparatively recent innovation which developed from starch recovery processes. Early starch recovery processes utilized the whole wheat kernel but could not be converted to gluten production because the process conditions were too harsh and destroyed or devitalized the gluten. On the other hand, dough ball or batter processing from wheat flour was relatively simple because the bran and the germ had been substantially removed in the milling process. In addition, high ash second clears worked well in the dough ball process and were available at attractive prices as a by-product of the flour milling industry. Consequently, wheat gluten processing has been flour oriented for decades and no need has apparently existed to motivate the development of a process starting from the whole wheat kernel. However, improvements in milling techniques coupled with a drastic decline in the number of operative flour mills has led to current shortages of and higher prices for clears. In fact, millions of pounds of vital wheat gluten are imported by the United States each year to meet demands domestic producers cannot fill.
On process for vital wheat gluten-starch separation and gluten recovery which utilizes the whole wheat kernel as the starting material is taught in U.S. Pat. No. 3,891,613. According to that process the whole wheat kernel is tempered in water and flaked and the flakes are thereafter hydrated to saturation to form a thick, dough-like mass and mechanically worked in the presence of water to wash the wheat kernel components from the gluten. However, the continuous processing of the whole wheat kernel in water during hydrating and mechanical working has been found to cause a pigmentation transfer from the bran and germ to the final dried products of the process. The resulting coloration of the products is undesirable for aesthetic reasons and may cause reduction in product shelf life. In addition, flaking of the tempered whole wheat kernel in a flaking or roller mill has been found to cause needless damage to the starch component of the kernel.